NO332431B1 - Decoders and methods for controlling the display of multiple digital television channels in respective windows of a mosaic formation - Google Patents

Abstract

A digital television system is provided which has the distinctive feature that access rights to a program or channel are received and analyzed by a decoder to determine whether a user should be given or prohibited full audio access and visual access to the respective program or channel when it is displayed. in a mosaic window.

Description

The present invention relates to a digital television system with several channels and in particular to those aspects of a system that relate to finding or "navigating" between channels.

One of the advantages of digital television lies in the number of channels available in such systems and the flexibility available to a provider of television services with regard to which channel choices can be made available to a subscriber to a service. Apart from a standard set of subscription channels, the system can also include other access-controlled channels, such as e.g. a channel with payment per display to enable a subscriber to pay for a particular movie, sporting event, etc.

In addition, the digital television system can give a viewer access to a number of other services of an interactive type, such as text-based program overviews, weather maps, etc. These services can be linked to reserved digital television channels that are used to carry the information. Additional other menu-based services may be offered that enable a user to access certain common information in a series of so-called drop-down menus while viewing a broadcast program. These services are operated by using so-called pilot information which is carried on the same channel as the usual audiovisual channels.

Although the viewer benefits from the increased selection available, the large number of channels and services available can prove distracting and in practice a viewer can often have difficulty managing the viewing options available. In addition, the existing tools often fail to find out how to properly handle the interface between the "navigator" and the access-controlled channels, some of which need not be accessible to a particular user.

In its broadest and/or specific aspects, it is an object of the present invention to overcome any or all of these problems, by facilitating a user's navigation among channels while respecting the access control restrictions.

According to a first aspect, the present invention provides a decoder for controlling the presentation of several digital television channels in respective windows in a mosaic formation, the decoder having as a distinctive feature that it includes equipment for receiving access rights for a program or a channel, and equipment for accordance with the received access rights to deny a user full audio and video access to said program or channel when it is displayed in a window.

The use of mosaic-shaped displays of available channels to assist in navigation among channels is known in the art. For example, the publication EP 0 725 538 A describes an electronic program overview system where nine small screen images reduced from nine screen images taken from different programs are arranged in a 3x3 matrix for the purpose of constructing a picture-in-picture display for program selection. Six such image displays are multiplexed via a single transmission channel. Each image display received is displayed in the form of 3x3 small screens with full movement, so that the viewer can select a desired program from the image display, for viewing in full size on the television screen. Furthermore, the publications US 5 585 866 and WO 97/34413 deal with similar aspects of the state of the art.

However, such mosaic tools give a user full access to all available channels, albeit in a reduced form. If digital audio for this channel is also available, a user can watch and listen to e.g. an entire program that is normally only available with a special subscription or against payment, but which is shown here in a window in the mosaic display. The present invention overcomes this problem.

The decoder preferably comprises equipment, such as a receiver, for receiving access rights data together with audiovisual data to create the mosaic. In order to allow a user to obtain full access rights to a program and/or a channel, the decoder preferably includes equipment, such as an interface, to issue a request for full audio and visual access to the channel or program displayed in a window.

The access rights information can be used by the decoder in many different ways.

With e.g. in an embodiment where a cursor is used to select a desired channel and the audio information is generated by the decoder in response to the location of the cursor, the decoder may be adapted to allow or prevent the generation of audio information for a program or channel, if access regulated.

The decoder thus preferably includes equipment, such as a user program, to generate a marker for display together with the mosaic formation, so that the marker and the windows in the mosaic formation can optionally be moved in relation to each other to enable the selection of a desired window within the mosaic formation. It is even better if this equipment generates a marker for display together with the mosaic formation, so that the marker can be moved optionally over the windows in the mosaic to enable the selection of a desired window within the mosaic formation.

The decoder can include equipment for generating audio information linked to a specific channel in response to the cursor being placed on said window that displays the specific channel and can also include equipment for preventing said audio information from being generated in accordance with received access rights.

The audio information can be deactivated for access-controlled programs or channels at any time, if the decoder does not have the access rights. Alternatively, the audio information can be prohibited if the cursor is placed on a prohibited mosaic window for longer than a predetermined time. The preventing/regulating equipment can thus be adapted to prohibit the generation of said audio information if the cursor is placed on a window for longer than a predetermined time.

In yet another embodiment, the interaction between the cursor and a mosaic window may depend on the access rights associated with the program or channel displayed in the relevant window. As an example, the decoder may be adapted to automatically reposition the cursor if the cursor is placed on a prohibited mosaic window corresponding to an access-controlled program or an access-controlled channel. The decoder thus includes equipment to automatically reposition the cursor if the cursor is placed on a window showing a program or a channel that is blocked for full audio and video access.

This repositioning can be performed instantaneously in the sense that the decoder does not allow the cursor to be placed directly on an access-controlled program or an access-controlled channel displayed in a mosaic window. Alternatively, the repositioning can be carried out after the expiry of a predetermined time. Thus, the repositioning equipment is preferably adapted to reposition the marker after the expiration of a predetermined time period. If e.g. an audio track is activated when a window is highlighted with the cursor, this time delay allows a user full access to a sample of a program over a period of time to enable the user to assess their interest in that program.

The repositioning of the cursor need not depend on the access rights of a channel and/or a program displayed in a window. In addition to or as an alternative to what is mentioned above, e.g. the decoder include means for automatically repositioning the cursor after the expiration of a predetermined period of time. This may enable a user to "surf" across the mosaic while audio information for each window in the mosaic is received in turn during this predetermined time period. This browsing work mode can be initiated by pressing a predetermined key on a remote control.

As an alternative to repositioning the cursor after the expiration of a predetermined time, the decoder may be adapted to automatically issue a request for full access rights to a channel and/or program to which full audio and video access is denied when the cursor is positioned on the window that displays the aforementioned channel and/or program for a predetermined period of time. This can open the way for automatic ordering of full access rights to a program and/or a channel without any further entries on the part of the user.

In addition or as an alternative to the above steps, the decoder may also be adapted to generate a message informing a user of the lack of access rights to a program or channel when the cursor is placed on a prohibited mosaic window. The decoder may thus comprise equipment for generating a message informing a user of the access rights to a program or a channel when the cursor is placed on such a window displaying either a program or a channel.

Alternatively or additionally, the decoder may simply prohibit the generation of video information in a mosaic window depending on the access rights associated with the program or channel normally displayed in that window. The decoder can thus include equipment to prevent the generation of at least part of the video information in said window depending on the access rights to either the program or the channel that is displayed in the relevant window.

A viewer's full access to at least a portion of the video information displayed in a window may be prohibited by utilizing one or more of a number of different methods. As an example, the decoder may comprise equipment for controlling the presentation of an image (still image) in the relevant window instead of said at least one part of video information. The image may include a brand or logo associated with the channel displayed in the window and/or an image associated with the program displayed in the window. Alternatively, the decoder may comprise equipment for controlling the presentation of an advertisement in the window instead of said at least one part of video information.

As another alternative, the decoder may comprise equipment for controlling the presentation of further video information in the window instead of said at least one part of the video information. This additional video information may include encouraging or promotional video information, such as a trailer or "trailer" of bits of an upcoming program to be shown on the channel displayed in that window.

The access rights to a program and/or a channel typically include information relating to the nature of the program or channel, such as e.g. if the channel is a subscription channel, if the program is an event with payment per display, etc. As well as being leveraged to allow or deny full video and audio access to the program and/or channel when displaying in a window in the mosaic, these and other access rights can be used by the decoder to customize or "tailor " different features of

the presentation.

The decoder can e.g. include means for changing an attribute at the cursor depending on a characteristic of either the program or the channel being displayed in a window. This characteristic can e.g. include the program's "rating" or age grading (such as adults-only, or children's programs), the program's subject or theme (e.g. sports, nature/wildlife, politics), whether the program is a pay-per-view event. display, etc. In addition, programs and/or channels can be grouped in accordance with a user's choice of e.g. favorite channels and the cursor attribute changes accordingly each time it is placed on a window that displays one of the user's favorite channels. This may facilitate the user's identification of certain channels and programs displayed in the mosaic.

In one embodiment, the changing equipment is arranged to change the marker's color depending on said characteristic of at least one program or channel that is displayed in the window on which the marker is placed. However, other attributes of the marker, such as its size and shape, can be changed according to this characteristic.

The decoder may include equipment for receiving data from a hand-held remote control connected to the decoder for assigning said characteristics and equipment for assigning said characteristics in response to the received data. This may enable the user to assign a channel as a favorite channel using the remote control at e.g. to press a predetermined key on the controller when the cursor is placed on the window showing the channel in question. Alternatively, the decoder can include equipment for generating a list of channels displayed in the mosaic, so that the user can select channels from the list, as favorite channels, by pressing the correct keys on the remote control.

The decoder may be arranged to perform one of a number of operations when the user presses a predetermined key on the remote control while the cursor is positioned on a window. The decoder can e.g. include equipment to tune the decoder to a channel displayed in the selected window. This can enable the selected channel to be displayed by filling the television screen when selecting the window that displays the channel in question. As an alternative to having to press a key on the remote control, the decoder can be arranged so that it automatically tunes to the channel after a predetermined period of time has elapsed.

Alternatively or additionally, the decoder may comprise equipment for generating a display comprising information relating to the program displayed in the selected window. For example, a short summary of the program shown on the channel can be displayed together with the start time, duration and/or end time when a predetermined key is pressed on the remote control while the cursor is placed on the window showing the channel in question.

This information can be received by the decoder together with the audiovisual data for the relevant program and stored in a memory in the remote control for retrieval and display at the request of the user. Alternatively, the decoder can download this information for display when necessary. Another alternative implies that the decoder may include equipment for communicating with a communication center to obtain said information relating to the program displayed in the desired window. The communication equipment may comprise a modem to call up said communication center, to deliver a request for said information to the communication center.

The decoder may also include means for generating a display comprising a schedule of upcoming programs on the channel displayed in the selected window. This plan can be received by the decoder together with the audiovisual data for the displayed channel. Alternatively, the decoder can download this plan for display whenever necessary. Another option implies that the decoder may include equipment for communicating with a communication center to achieve the plan. The communication equipment may include a modem to call the communication center, to deliver a request for the plan to the communication center.

The schedule of upcoming programs may include presentation of the program schedule information in the form of text. Alternatively, the plan of upcoming programs can include the display of several images in the form of images (still images) linked to the individual upcoming programs in respective windows in the mosaic.

Several pictorial representations can be linked to upcoming programs to be shown simultaneously on the respective digital television channels. For example, these upcoming programs may be shown on respective digital television channels during a future time period. When the cursor is placed on one of these images, information relating to the programme, such as the programme's title, start time, duration and/or end time, can be displayed.

At least one image in the set of pictorial images may include the video tape length (video footage) associated with the future program in question.

In one embodiment, the receiving equipment is adapted to receive said access rights from a hand-held remote control connected to the decoder. This may enable a user to prevent video and/or audio access to one or more of the channels displayed in windows in the mosaic and e.g. the user may wish to restrict all access to channels that normally show adult programmes. When e.g. cursor is placed on a window to which the user wishes to block all access, the user can, by pressing one or more keys on the remote control, instruct the decoder to prevent all access to the channel displayed in the relevant window.

Preferably, the receiving equipment is adapted to receive a PIN code from the hand-held remote control, the decoder comprising equipment to authenticate the received PIN code and, upon authentication of the received PIN code, to allow the receipt of access rights. This can add a level of security with regard to the transfer of access rights, thereby preventing the access rights from being changed by an unauthorized user.

In one mode of operation, the channels are displayed in a form determined by the broadcaster of the audiovisual data for the channels. Thus, a user's various favorite channels can be arbitrarily spread out in the mosaic. In order to make it possible to change the position of the different windows in the mosaic, the decoder in one embodiment includes positioning control equipment to control the relative positions of the windows within a mosaic. In a preferred embodiment, the decoder comprises positioning control equipment to change the relative positions of the windows within the mosaic.

In one embodiment, the positioning control equipment can be arranged to control the relative positions of said windows in response to received access rights to the channels or programs displayed in the windows. For example, programs and channels with payment per views to which the user does not have full access rights are displayed in neighboring windows in the mosaic.

In one embodiment, the positioning control equipment is arranged to control the relative positions of the windows in response to window positioning data to control the relative positions of the windows within the mosaic. In one embodiment, the decoder includes equipment for receiving said window positioning data from a hand-held remote control connected to the decoder. This makes it possible for a user to easily change the relative positions of the windows in the mosaic by e.g. to press one or more keys on the remote control.

The positioning control equipment can be arranged to control the relative positions of the windows in the mosaic in accordance with a program characteristic for the programs that are normally shown on the channels that are displayed in the windows. As an example, the positioning control device may be arranged to group together windows that typically display programs having the same theme, such as sports, nature, children's programs, adult programs, etc. Additionally or alternatively, the positioning control device may be arranged to group together windows that show off channels that usually show events with payment per display.

The positioning control equipment may be arranged to maintain a window displaying either a particular channel or a particular program at a constant position in the mosaic. This window can e.g. be the window in the mosaic that displays the channel that has been displayed immediately before the display of the mosaic shape.

In another aspect, the present invention also provides a method for controlling the presentation of several digital television channels in respective windows in a mosaic formation, the method having as a distinctive feature that it includes receiving access rights for either a program or a channel and that a user in accordance with the access rights received, full audio and visual access to said one program or channel is prohibited when it is displayed in a window.

The device features described are also applicable to method aspects of the present invention, and vice versa.

As the term "digital television system" is used herein, it includes any transmission system for transmitting or broadcasting e.g. primarily audiovisual or digital multimedia data. Although the present invention is particularly applicable to a broadcast-based digital television system, the invention can also be applied to fixed telecommunications networks for Internet applications of the multimedia type, a closed television network, etc. The term also includes a system that utilizes any satellite, ground, cable or other communication link.

The term "decoder" or "receiver/decoder" as used herein may denote a receiver for receiving either coded or uncoded signals, such as television and/or radio signals that may be broadcast or transmitted by means of some equipment . The term can also denote a decoder for decoding received signals. Embodiments of such receiver/decoders may include a decoder integrated with a receiver to decode received signals, such as in a "set-top box", a decoder operating in combination with a physically separate receiver, or a decoder having additional functions , such as a web browser, a video recorder or a television set.

By way of example only, a preferred embodiment of the present invention will now be described with reference to the attached drawings, in which: Fig. 1 shows a digital television system as it can be adapted according to the present

invention,

fig. 2 shows an overview of the elements of a decoder for use in a digital television system,

fig. 3 shows a handheld remote control for use with the decoder shown in Fig. 2, fig. 4 shows a screen display associated with a first embodiment of a mosaic of

channels,

fig. 5 shows the cursor in a different position in the screen display shown in fig. 4,

fig. 6 shows another screen display associated with a mosaic of channels,

fig. 7 shows subscription information in the screen display shown in fig. 6, when a

user does not have full rights to a channel,

fig. 8 shows the elements of a transmission system associated with the generation of the mosaic, fig. 9 shows a screen display associated with a second embodiment of a mosaic of channels,

fig. 10 shows a cursor placed in the screen display shown in fig. 9,

fig. 11 shows subscription information in the screen display shown in fig. 9, when a

user does not have full rights to a channel,

fig. 12 shows a screen display of an electronic program overview in the form of a

mosaic of windows,

fig. 13 shows a screen display associated with a mosaic of radio channels,

fig. 14 shows a screen display of information relating to a radio channel, and fig. 15 shows a screen display associated with a mosaic of interactive user programs.

An overview of a digital television system 1 is shown in Fig. 1. The invention comprises a very common digital television system 2 which uses the known compression system MPEG-2 to send compressed digital signals. In more detail, an MPEG-2 compressor 3 in a broadcasting center receives a digital signal stream (typically a stream of video signals). The compactor 3 is connected to a multiplexer and reverser 4 via a connection 5.

The multiplexer 4 receives several additional input signals, assembles the transport stream and sends compressed digital signals to a transmitter 6 in the broadcasting center via a connection 7 which can of course have many kinds of designs, including telecommunications connections. The transmitter 6 sends out electromagnetic signals via a connection 8 upwards towards a satellite transponder 9 where they are electronically processed and broadcast via a fictitious connection 10 downwards to an earth receiver 12 which conventionally has the form of a reflector dish which is owned or rented by the end user. The signals received by the receiver 12 are transmitted to an integrated receiver/decoder 13 which is owned or rented by the end user and is connected to the end user's television set 14. The receiver/decoder 13 decodes the compressed MPEG-2 signal into a television signal for the television set 14.

Other transport channels for the transmission of data are of course possible, such as terrestrial broadcasting, cable transmission, combined satellite/cable connections, telephone networks, etc.

In a multi-channel system, the multiplexer 4 handles audio and video information received from a number of parallel sources and cooperates with the transmitter 6 to broadcast the information on a corresponding number of channels. In addition to audiovisual information, messages or user programs or any other type of digital data may be introduced into any or all of these channels interleaved with the transmitted digital audio and video information.

A conditional access system 15 is connected to the multiplexer 4 and the receiver/decoder 13 and is located partly in the broadcasting center and partly in the decoder. It enables the end user to access digital television broadcasts from one or more broadcasting providers. A smart card capable of deciphering messages relating to commercial offers (ie one or more television programs sold by the broadcasting provider) can be inserted into the receiver/decoder 13. Using the decoder 13 and the smart card, the end user can purchase commercial offers in either a subscription mode or a mode with payment per display.

As mentioned above, the programs transmitted by the system are recast in the multiplexer 4 while the conditions and encryption keys applied to a given broadcast are determined by the access control system 15. Broadcasting of recast data in this way is well known in the pay television field. The discarded data is typically sent together with a control word for restoring the data, the control word itself being encrypted with a so-called evaluation key and transmitted in encrypted form.

The scrambled data and encrypted control word are then received by the decoder 13 which has access to an equivalent of the evaluation key stored on a smart card inserted in the decoder to decrypt the encrypted control word and then recover the transmitted data. A subscriber who has paid will e.g. in a monthly broadcast entitlement management message (EMM - Entitlement Management Message) receive the evaluation key that is necessary to decrypt the encrypted control word in order to enable viewing of the broadcast.

An interactive system 16 which is also connected to the multiplexer 4 and the receiver/decoder 13 and is once again located partly in the broadcast center and partly in the decoder, enables the end user to interact with various user programs via a modem connected reverse channel 17. The modem connected reverse channel can also used for messages used in the conditional access system 15. For example, an interactive system may be used to enable a viewer to communicate instantaneously with the dispatch center to request permission to view a particular event, download a user program, etc. .

With reference to fig. 2, the elements of the receiver/decoder 13 or set-top box will now be described. The elements shown in this figure will be described in the form of function blocks.

The decoder 13 comprises a central processor 20 which has associated memory elements, and is adapted to receive input data from a serial interface 21, a parallel interface 22, a modem 23 (connected to the modem-connected reverse channel 17 shown in Fig. 1) and reverse contacts 24 on decoder front panel.

The decoder is additionally adapted to receive input signals from an infrared remote control 25 via a control unit 26 and also has two smart card readers 27, 28 adapted to read bank and subscription smart cards 29, 30 respectively. The subscription smart card reader 28 engages with an inserted subscription card 30 and with a conditional access unit 29 to feed the necessary control word to a demultiplexer/restorer 30 to enable the encrypted broadcast signal to be recovered. The decoder also has a conventional tuner 31 and demodulator 32 to receive and demodulate satellite transmissions before they are filtered and demultiplexed by the unit 30.

The processing of data in the decoder is generally handled by the central processor 20. In the case of received audio and video signals, the MPEG packets containing these signals will be demultiplexed and filtered to transmit audio and video data in real time in the form of a packed elementary stream (PES) of audio and video data to reserved audio and video processors or decoders 33, 34. The converted output from the audio processor 33 is transferred to a preamplifier 35 and then via the receiver/decoder's audio output. The converted output from the video processor 34 is transferred via a graphics processor 36 and a PAIVSECAM encoder 37 to the receiver/decoder's video output.

With reference to fig. 2, the graphics processor 36 is preferably designed to generate a screen display that juxtaposes moving images with superimposed text or other images. Specifically, it can combine 4 layers, namely a still image layer, a "live" image layer, a graphics layer and a marker layer. In addition, the graphics processor 36 receives graphic data for display (such as generated images, etc.) from the central processor 20 and combines this information with information received from the video processor 34 to generate a screen display.

The software architecture of the central processor may correspond to that used in known decoders and will not be described in any detail here. It can e.g. be based on a virtual machine that interacts via an interface layer with a lower-level operating system implemented in the decoder's hardware components. With regard to hardware architecture, the decoder will be equipped with a processor, memory elements, such as ROM, RAM, FLASH memory, etc., as in known decoders.

The central processor 20 can be adapted to execute a number of user programs that determine the functionality of the decoder. A user program entered into the decoder corresponds to a code section entered into the machine, which allows control of e.g. higher level functions in the machine. Typical user programs may include generating a graphic sequence on the television screen in response to a command from the remote control, or sending a message via the modem to a server associated with the digital broadcasting system.

As will be described later, a user program according to the present invention is adapted to generate viewer screens, markers and program information that is superimposed on or replaces the normal television presentation and is linked to navigation between a number of channels or interactive services proposed by the system. The information that is displayed may include menus that are essentially unchanged and/or data that is updated using information contained in one or more channels' MPEG transport stream.

The user programs may be persistent user programs stored in the decoder's ROM or FLASH memory, or the user programs may be broadcast and downloaded via an interface in the decoder, or in particular such as the serial interface 23, a smart card reader 27, etc. The user programs may include navigation tools, program overviews , games, interactive services, "teleshopping" programs, as well as initiating user programs that enable the decoder to become immediately operational at startup, as well as user programs for configuring the decoder.

The user programs are stored in memory locations in the decoder and are represented as resource files including graphic object description files, device files, variable block files, instruction sequence files, user program files, data files, etc.

Conventionally, the user programs are downloaded into the decoder via the broadcast connection, divided into modules, each module corresponding to one or more MPEG tables. Each MPEG table can be divided into a number of sections. When data transfer also takes place via the serial and parallel ports, the modules are likewise split into tables and sections, the size of the sections depending on the channel used.

In the case of broadcast broadcasts, the modules are transported in the form of data packets in different types of data streams, such as in a video data stream, an audio data stream, and a text data stream. According to MPEG standards, each packet is preceded by a packet identifier (PID) of 13 bits, i.e. a PID for each packet transported in the MPEG stream. For a given frequency channel, one or more "program map tables" (PMTs - Program Map Tables) contain a list of the different data streams in the relevant channel and define the content of each stream according to its respective PID. The PMT table or tables are accessible via a parent program access table (PAT - Program Me Access Ta ble).

In a digital broadcasting system, information is carried on several frequency channels with a fixed and predetermined bandwidth. A single frequency channel can accommodate several audio and/or video data streams. A single video stream can e.g. be linked to multiple audio streams dubbing a program in a number of languages. Alternatively or in addition, several video streams can be contained in the packet stream linked to the frequency channel and which e.g. shows the same sporting event from different camera positions. Although these different audio and video streams are broadcast on the same frequency channel, a viewer can perceive a change of the audio/video stream within that frequency channel as corresponding to a real channel change.

In addition to conventional audiovisual program information, other data can be carried on the frequency channel. As will be described below, this data may include menu display information related to updated program summaries, etc. Such data's PID values may again be available via a PMT table.

In order to produce a constant interface, some information is necessarily broadcast on all frequency channels. As an example, information relating to a user program of the "pilot" type, which indicates common program information and the options available to the user, can be broadcast on all frequency channels, so that a user can always call up this information regardless of the program or channel he look at. In this way, the continuity of the interface is ensured.

With reference to fig. 3, the set of control keys associated with the hand-held remote control 25 for the receiver/decoder will now be described. This remote control layout corresponds to the one currently supplied with the existing Canal+ Mediahighway digital decoder system. As will be appreciated, the decoder's response to activation of a particular control key on the handset is programmable and may vary in accordance with the user program loaded into the decoder. Thus, although certain functions (on/off, mute, etc.) are universal, others can be changed according to the decoder configuration.

As shown, the remote control 25 has a PROG key 40 and a PILOT key 41. In the existing Canal+ Mediahighway decoder system, these control keys respectively call up a program guide which lists the programs available on each channel and a "pilot user program" which provides information about the program being shown on the relevant channel, as well as a certain amount of information about other programs that can be seen on this and other channels at the moment, in the near future, etc.

In the context of the present invention, activation of the PROG key 40 on the remote control invokes a more generalized main service menu, the program overview being available as an option in this menu along with other services, such as interactive purchasing user programs, etc. The user program invoked with the pilot key 41 remains in essentially unchanged.

The remote control further has a set of direction-determining navigation keys 42 to

control the movement of a cursor on the screen within a menu display, as well as an "OK" control key 43 for selecting an item or entry highlighted by the cursor.

A set of number keys 44 enables direct selection of a numbered channel, entry of numerical data, such as credit card number, PIN code, etc. The number keys 44 may also be associated with entry of secondary data sets, such as the days of the week, day/night/evening, etc. This data can be printed above the control keys and can be used when programming a timer user program, during navigation in a program overview, etc.

The remote control 25 also has a preference control key 45 which gives access to a menu list of a limited number of preferred channels selected by the user. In this way, a user can quickly switch between the channels he or she watches most often. Control key 46 is used to exit an activated user program or a displayed menu. The SERV control key 47 is used to call up a summary of the services available within an activated user program, such as a user guide for a purchasing user program.

The "+" control key 48 provides access to a menu that allows selection of subtitles in a number of languages and/or selection of the language used in the audio track accompanying the displayed program.

The PERSO control key 49 invokes a user program which enables a user to set certain basic personal functions of the decoder, including the volume of the audio output from the decoder, characteristics of the video output of the decoder, etc.

The control keys A - E 50 are not generally associated with a specific type of function, but they can be used by certain user programs and as an opportunity for the programmer to activate special functions, such as return to a previous menu, etc.

Finally, the mute control key 51 disables or enables the audio accompanying the displayed channel, while the TV/SAT control key 52 enables a user to switch between channels received via a satellite input and those received via a conventional antenna, while the "standby" key 53 enables a remote user to turn the decoder on and off.

With reference to fig. 4 is one of the services offered a grid/raster or mosaic showing the content of all channels currently being broadcast to the decoder. When selecting this service, the decoder switches to the frequency channel associated with this service and the mosaic 80 shown in fig. 4 is displayed. In this embodiment, the mosaic 80 is broadcast on channel no. 8, so that when the number key "8" is selected on the remote control, the decoder tunes to this channel. In an alternative embodiment, the remote control can have a reserved control key for setting this frequency channel.

The mosaic 80 consists of a number of miniature screen windows 81, each of which in real time shows the program being shown on a channel and each of which, by the reference number 82, has an indication of the name of the channel shown in the display window.

duet 81. The mosaic also has a general information field 84.

A user program in the decoder generates a movable frame marker shown at reference number 83. This marker can be moved horizontally and vertically using the navigation arrows on the remote control. As an example, marker 83 in FIG. 5 has been moved to select the third down and third up windows. The title of the program currently displayed on the channel displayed in this window is indicated in the display field 84. In addition, the decoder selects and plays the audio stream associated with this channel. A press of "OK" on the remote control then causes the decoder to tune in to the selected channel shown in the relevant window.

The mosaic shown in fig. 4 shows 20 channels. In practice, up to 60 or more channels can be received by a decoder. In that case, access to other program mosaics may be necessary. When the cursor e.g. is positioned on window 84", as shown in Fig. 4, selecting the right-facing navigation arrow will cause the display to change to another mosaic of 20 programs, as shown in Fig. 6. When the cursor is on left side of the grid 80, likewise, selecting the left-facing navigation arrow will cause the display to change to show another program mosaic. The mosaic screens can also be "looped", so that when the last mosaic screen is left, the user will be brought back to the first screen, etc.

The program mosaic shown in fig. 4 shows a selection of all program channels that are broadcast to the decoder. In some cases, however, the decoder does not need to have full access rights to all channels. For example, some channels may be reserved for pay-per-view programmes. display or require a further subscription from the user. In this case, it is undesirable for a user to have full audio and video access to the program, even to a reduced screen version displayed in viewer windows 81.

Accordingly, in one embodiment, the decoder user program that manages the mosaic display is adapted to monitor the time that the frame marker remains in a single position. After a period of e.g. 30 sec. the user program will compare the access rights for the channel in question with the access rights in the decoder, to verify whether a user has full access to the program or channel displayed in the mosaic window, or not.

If the decoder does not have the necessary access rights, the user program ensures that the audio output is cut off after 30 seconds, so that the user can no longer hear the audio track associated with the program in question.

If the user does not have the necessary access rights, the frame cursor will jump to another window in this mosaic, such as the first element in the upper left corner of the first screen. Alternatively, the cursor can jump to a window element in another mosaic. Over a period of 5 min. or the like thereafter, the user program may refuse to allow the cursor to be re-positioned on the access-denied window.

In this case, the user program can suggest to the user the possibility of paying for access to the relevant channel, as shown by the reference number 86 in fig. 7. If the user agrees, the user program can switch directly to the relevant channel by e.g. to use credits stored in the user's subscription card. Alternatively, the user program may activate the payment menu screens necessary to allow the user to subscribe. Such steps are standard and will not be discussed in any detail here. As rights are purchased for events with payment per display, the control 20 under control from a user program can generate a drawn image or a symbol (icon) representing the purchase of an event. The control can e.g. generate a drawing of a shopping cart that begins to fill as events are purchased.

As an alternative to a timeout procedure, the user program can perform the necessary steps to reposition the cursor and/or interrupt the audio output as soon as the cursor stops on a window element for a program or channel to which access is not available.

The repositioning of the cursor need not depend on the access rights of a channel and/or a program displayed in a window. In addition to or as an alternative to what has been said above, the decoder's user program can e.g. be adapted to automatically reposition the cursor after the expiration of a predetermined time. This may enable a user to "surf" across the mosaic while audio information for each window in the mosaic is received in turn during this time slot. This browsing work mode can be initiated by pressing a predetermined key on the remote control.

As an alternative to repositioning the cursor after the expiration of a predetermined time, the user program may be adapted to automatically issue a request for full access rights to a channel and/or program to which full audio and visual access is prohibited, when the cursor in a predetermined time period is located on the window that displays this channel and/or this programme. This can enable automatic ordering of full access rights to a program and/or channel without any further input from the user.

In addition to or as an alternative to intercepting the audio output, the user program can also ensure that the video output is intercepted. In some cases, when e.g. adult material is displayed, the decoder can in any case darken the video display and cut off the audio output for the program and channel in question, so that only channel and program title information is displayed in fields 84, 82. Since such material can be deleted from all mosaic displays independently of the decoder's access rights, this step can also be performed upstream of the decoder, at the transmitter end.

With reference to fig. 8, the architecture of the elements of the transmission system related to the generation of the mosaic channel will now be described. Video signals from 60 channels are received by a server 90 linked to a station 91. The task of the server 90 is to filter out such video signals that are not to be incorporated into the mosaic, e.g. video signals associated with adult-only channels, etc. The processed signals are then transmitted to a processor 92 which resizes and repositions the video signals within a picture screen display, thus generating three grid or mosaic screens shown at reference numeral 93, which are then fed to the multiplexer 4.

In a similar manner, audio signals from each of the channels are filtered at reference numeral 94 and then assembled and assigned PID values at reference numeral 95 before being fed to the multiplexer 4.

In addition to the broadcast audio and video data, additional data can be entered by means of an SA/DA injection server 96 and an associated workstation 97. In particular, the server and the station enter configuration data relating to the configuration of the elements in the mosaic together with pilot data containing the minimum information regarding to the programs broadcast on each channel. The pilot data may correspond to that used by the "pilot user program" and will be utilized by the user program to generate the initial information field 84 at the top of the mosaic screen.

The configuration data typically includes a description of the number of mosaics, the size and position of each screen element within each mosaic, the frame cursor's desired size, and the limits of cursor movement. This information will be used to enable the associated decoder user program to position and move the frame marker correctly. In addition, the data includes the position of each channel in the mosaics (page number and coordinates), the PID of the associated audio track in the compiled audio stream and the channel reference in the pilot data.

To enable the decoder user program to switch directly to a desired channel, the configuration data should also include details of the channel (frequency, PID value) associated with a given element. Access details (pay per view, subscription, etc.) may also be incorporated to enable the decoder's user program to perform the operations described above and prevent a user from viewing and listening to a channel where access is prohibited. Finally, the configuration data contains the PID value for each mosaic page and a standard introductory message (if any) associated with that mosaic page.

An example of a mosaic form where at least part of the video output is darkened is described below with reference to fig. 9 - 11.

The mosaic 100 is broadcast on channel no. 1 and when the number key "1" is selected on the remote control, the decoder is tuned to this frequency channel. In an alternative embodiment, the remote control can have a reserved control key for tuning to this frequency channel.

The mosaic 100 consists of a thumbnail screen window 101 which in real time shows previews with bits of future events to be shown on one or more of the other channels and four thumbnail screen windows 102 which all show in real time the program shown on the respective channel. The mosaic also contains a general information field 104 and a time and date field 106. In addition to the mosaic windows 101, 102, the mosaic form 100 contains push button elements 108 whose purpose will be described below.

When the mosaic 100 is first activated, the audio output is linked to the channel displayed in the window 101 and, as shown in fig. 9, the general information field 104 informs the user how to move around the mosaic shape 100. By pressing one of the arrow keys (navigation arrows) on the remote control, a user program in the decoder generates a movable frame marker around one of the windows 102, as shown at reference numeral 110 in fig. 10, or one of the push button elements 108. This cursor can be moved horizontally and vertically by using the arrow keys on the remote control.

The push button elements 108 provide quick access to one of the channels identified by the text that appears in each push button element. Placed e.g. the cursor over the push-button element 108 bearing the words "CANAL SATELLITE" and "OK" is pressed, this causes the decoder to tune to the CANAL SATELLITE frequency channel.

With the cursor 110 placed on one of the windows 102, the title of the program currently shown on the channel displayed in the window in question is entered in the general information field 104. In addition, the decoder selects and plays the audio stream associated with this channel. Pressing "OK" on the remote control will cause the decoder to tune to the channel shown in this window.

As discussed above with reference to fig. 4-7 the decoder in some cases cannot

have full access rights to all channels. Some channels can e.g. be reserved for programs with payment per viewing or they may require an additional subscription from the subscriber. In this case, it is not desirable that the user has full audio and video access to a program that is displayed in the viewer windows 102. It is particularly desirable to have restrictions with regard to the video output in the mosaic 100, as the window 102 is sufficiently large for a viewer to comfortably way can look at a program to which he may not have full access rights.

Accordingly, in one embodiment, the decoder's user program that manages the mosaic display is adapted to monitor the time that the frame marker 110 remains in one and the same position. After a period of e.g. 30 sec. the user program will compare the access rights for the channel in question with the access rights in the decoder in order to confirm whether or not a user has full access to the program or channel displayed in the mosaic window 102.

If the decoder does not have the necessary access rights, the user program ensures that the audio output is switched to the one associated with the channel displayed in window 101 and moves the marker accordingly (in this embodiment, the marker is not generated when the audio output is associated with the channel displayed forward in window 101, although this is not essential). At about the same time, the video output for the channel displayed in the mosaic window 102 is cut off, as indicated by reference number 101 in fig. 11, thereby preventing the user from viewing the programme. When this happens, the user program can suggest to the user the possibility of paying for access to the relevant channel, as shown by reference number 104 in fig. 11.

The "darkening" of the video output to one or more of the windows 102 can be achieved by simply cutting off the video output to the part of the screen where the window is located. However, the obscuration may be achieved by any of a number of different techniques, as discussed below.

As previously mentioned, the decoder typically has a 4-layer structure to generate the image to be displayed on the television set, the four layers being a still image layer, a layer of "live" images, a graphics layer and a marker layer. The graphics layer is preferably used both for symbols/icons (typical geometric shapes) and text/titles (usually, but not always, subtitles). The decoder's user program can control the presentation of text, images or combinations of text and images in the still image layer to be superimposed on at least part of the mosaic window 102, thereby hiding the video image displayed in this window.

This text and/or image display can take any suitable form. The user program can e.g. control the generation of: (i) a square, rectangle or other geometric shape that at least partially overlies the window;

(ii) a logo for the channel displayed in the relevant window,

(iii) a text advertisement for a program that is either currently being shown or to be shown in the future on the relevant channel, and/or (iv) a still image relating to a program that is either currently being shown or to be shown in the future on the relevant channel.

These parts of the presentation may be previously stored in the decoder's memory for retrieval and use as needed. The text and/or image can e.g. is downloaded by the decoder along with the audiovisual information for the mosaic 100.

By additionally producing a layer for moving images, the mosaic window 102 can alternatively or additionally be covered with an inviting or promotional video feature for the channel in question. This video footage can also be downloaded by the decoder along with the audiovisual information for the mosaic 100.

The decoder can be programmed in such a way that a mosaic channel will always be displayed when the decoder is started. While the cursor can also be fixed on the same channel every time the mosaic formation is first activated, there are other possibilities as well. When the decoder is activated, e.g. a mosaic will be displayed along with a cursor highlighting the last channel the user watched. When switching between mosaic screens, a channel can be seen on all these screens. In fig. 5 and 6 become e.g. channel no. 9 shown. Likewise, when a user moves from a channel to the mosaic channel, the mosaic screen containing that channel highlighted by the cursor can be displayed, giving a sort of "zooming out" effect from the full-screen display of the channel to a thumbnail version in a window element in the mosaic.

If, with the embodiments described above, the "OK" key is pressed when the cursor is positioned on a specific mosaic window, this causes the decoder to tune to the frequency of the channel displayed in that specific mosaic window. However, pressing an alternative key on the remote control can activate one of several different user programs stored in the decoder. For example, pressing one of the number keys B-E (key A is typically reserved for adjusting the audio volume setting, as shown in Fig. 4) can cause the decoder to start displaying an electronic program overview (EPG - Electronic Program Guide) associated with it channel that is displayed in the window where the cursor is placed.

The program overview EPG can take one of many forms. The EPG can e.g. include a text presentation of a schedule of upcoming programs on the channel. Such displays are well known in the field and will not be further described here. Alternatively, and as shown in fig. 12, the EPG may include a mosaic display 120 with multiple mosaic windows 122 (although only three windows are shown in FIG. 12, another number or arrangement of windows is possible). Each window contains an image (still image or moving image) of the future program together with an indication 124 of the relevant program's title. The mosaic also contains a general information field 126 which indicates the name of the channel and the time period covered by the mosaic 120.

A user program in the decoder generates a movable frame marker, shown at reference numeral 127. This marker can be moved horizontally and vertically using the navigation arrows (arrow keys) on the remote control. If the cursor is positioned on a window, this program's title and duration will be displayed, as shown by reference number 128 in fig. 12, together with a summary of the program's content, as shown at reference number 130 in fig. 12.

Access to other EPG mosaic displays for the channel may be required to display programs shown during a later time period. When e.g. cursor is placed on window 122 on the right side of the mosaic, selecting the right-facing navigation arrow will cause the display to move to another mosaic of three programs to be displayed at a later time. Similarly, when the cursor is on the left side of the mosaic 120, selecting the left-facing navigation arrow will cause the display to display another mosaic of three programs that were or will be displayed during a previous time period.

The display of the EPG can be started by tuning the decoder to a frequency channel containing the mosaic formation 120. Alternatively, the EPG can be received by the decoder together with the audiovisual information for the mosaic formations 80 and 100.

In addition to or as an alternative to the EPG form described with reference to fig. 12, the EPG may take the form of the mosaic formation 80 shown in FIG. 4, to display information relating to programs to be shown on all channels at a given time. In this example, each window 81 displays a still image or a moving image from a program to be shown at a specific time on the relevant channel, e.g. in one hour. The specific time is preferably indicated in the information

field 84. Moving the cursor around the mosaic causes the title of the selected program to be displayed in the information field 84. Selecting a specific key on the remote control causes the EPG to display a similar mosaic for another time, e.g. . two hours ahead.

As an alternative or in addition, the activation of the display of an EPG by pressing one of the keys B - E can cause the decoder to display additional information about the program displayed in the window on which the cursor is placed. This information preferably contains the programme's title, start time, end time and/or duration, as well as a summary of the programme's content. This additional information can be received by the decoder along with the audiovisual data for the information in the mosaic. Alternatively, it can be downloaded by the decoder for display as required.

In the embodiments of the mosaic formation described with reference to fig. 4-11, the cursor retains a constant size and a constant format (color, shape, etc.) when moved over the mosaic. Alternatively, the cursor's format may vary depending on a characteristic of the window on which the cursor is positioned. In one embodiment, the user program can change the marker's color depending on the access rights assigned to the program and/or the channel displayed in the window where the marker is placed. The marker can e.g. be green when the user has full access rights to the program and channel displayed in the window where the cursor is placed and red if the user does not have full access rights to the program and/or channel displayed in the window where the cursor is placed.

The marker can also be changed depending on characteristics different from these specific access rights. As an example, a user can assign a certain channel as a "favorite" channel by e.g. to press a predetermined key on the remote control when the cursor is placed on the window showing the channel in question. The assignment of this channel as a favorite channel is stored in the decoder's memory, so that when the cursor is later placed on the window that displays this channel, the cursor is displayed in a different color, e.g. in blue. As an alternative to selecting a favorite channel via the mosaic function, the user program stored in the decoder can display a list of all channels received by the decoder and the user can select different channels in the list as favorite channels using the remote control.

In addition to selecting the "favorite channel" using the cursor, the format of the cursor can be changed depending on the nature of the program displayed in the window where the cursor is placed. The marker can e.g. get a different format depending on the program's "rating" or age rating (such as a children's program, an adult-only program), the program's theme or subject (such as sports, nature/wildlife, politics), etc.

In another arrangement, the visual blackout and/or audio cut-off of certain windows in the mosaic formation may additionally be determined by the user. The user can e.g. wish to restrict all access to channels that usually show adult programmes, if such access is not restricted by the broadcaster. By pressing a key on the remote control when the cursor is placed on a window showing a program and/or a channel to which the user wishes to restrict access, the user can instruct the decoder to prevent all access to the channel in question. This information is stored in the decoder so that when the mosaic formation is then activated, the video and audio information for the relevant channel is blacked out/cut off. To ensure security, the decoder can request that a PIN code be entered by the user before the access rights are changed.

In the embodiments described with reference to fig. 4-11, the channels are displayed in a formation determined by the broadcaster of the audiovisual data for the channels. A user's various favorite channels can thus be arbitrarily scattered around the mosaic formation. In order to make it possible to position the different windows in the formation, the decoder's user program is in one embodiment designed to control the mutual position of the windows within the mosaic.

As previously mentioned, the decoder receives configuration data from the broadcaster, which contains a description of a number of mosaics as well as the size and location of each screen element within each mosaic. The decoder's user program is capable of rearranging the received position-determining information, so that the location of the screen image elements on the screen satisfies the user's requirements.

In one embodiment, the decoder's user program is adapted to control the relative position of the windows in the mosaic in response to the received access rights to the channels or programs displayed in the windows. For example, programs and channels with payment per display and to which the user does not have full access rights, are displayed in neighboring images of the mosaic formation.

Alternatively or additionally, the decoder's user program can be adapted to control the relative positions of the windows in a mosaic in response to commands issued from the remote control. This makes it possible for a user to easily change the relative position of the windows in the mosaic by e.g. to press one of the keys B - E on the remote control. For example, the mosaic windows can be sorted by theme, such as sports, nature/wildlife, children's programs, adult programs, etc. at the touch of a key.

Fig. 4-12 has illustrated arrangements of mosaic formations of windows showing programs shown on television channels. However, the mosaic formation is not limited to exclusively television programmes. For example, the mosaic formation 80 shown in FIG. 4 contain one or more windows linked to each of its radio channels. In this case, the mosaic windows for these radio channels display a mark or logo for the radio station.

The decoder can also receive frequency channels associated with the formation of other mosaics. As an example, fig. 13 a mosaic formation 140 with windows 142 where each window shows a logo for a radio channel and at the reference number 144 an indication of the name of the channel displayed in the window 142. The mosaic also contains a general information field 146. A user program in the decoder generates a moving frame marker, shown at reference number 148. This cursor can be moved horizontally and vertically using the navigation keys on the remote control. As an example, in fig. 5 the cursor 83 has been moved to select the first window down and the third up. An indication of the music currently playing on the channel displayed in this window is given in the information field 146. In addition, the decoder selects and plays the audio stream associated with this channel.

Pressing "OK" on the remote control causes the decoder to generate a display of additional information relating to the selected channel. As shown in fig. 14 get e.g. a press of "OK" on the remote control the decoder to generate a display 150 of additional information relating to the program currently being broadcast on the relevant channel. Alternatively, pressing "OK" can prompt the decoder in the form of a text, to display a schedule of upcoming music to be played on the channel or additional information relating to a piece of music currently playing.

Fig. 15 illustrates a mosaic formation 160 with windows 162 where each window is linked to its own interactive user program stored in the decoder's memory. Each window contains a mark or logo for the user program along with an indication 164 of the user program's name. A user program in the decoder generates a movable frame marker shown at reference numeral 166. This marker can be moved horizontally and vertically using the navigation arrow keys on the remote control. In fig. 15, as an example, the cursor has been moved to select the first window downwards and the second above. By pressing the "+" key on the remote control, the interactive user program is associated with the relevant logo, e.g. a "teleshopping" program, implemented.

Claims (76)

1. Decoder for controlling the presentation of several digital television channels in respective windows (81, 102) in a mosaic formation (80, 100), characterized in that the decoder (13) comprises equipment (12, 26) for receiving access rights for a program or a channel, and equipment (20) to, in accordance with the received access rights, prohibit a user from full audio and video access to said program or channel when it is displayed in a window (81, 102). 2. A decoder as set forth in claim 1, comprising means (12) for receiving access rights data together with audiovisual data to create the mosaic (80, 100). 3. Decoder as stated in claim 2, and which comprises equipment (20) for issuing a request for full audio and video access to a channel or a program displayed in a window (81, 102). 4. Decoder as stated in one of the preceding claims, and comprising equipment (20) for generating a marker (83, 110) for display together with the mosaic formation (80, 100), said marker (83, 110) and said windows (81, 102) in the mosaic formation (80, 100) are optionally movable relative to each other to enable selection of a desired window within the mosaic formation (80, 100). 5. Decoder as stated in claim 4, and which includes equipment (33) for generating audio information related to a specific channel, in response to the cursor being placed on the window (81, 102) which displays said specific channel. 6. Decoder as stated in claim 5, and which includes equipment (20) to prohibit the generation of said audio information in accordance with received access rights. 7. Decoder as stated in claim 6, and where the prohibiting equipment (20) is adapted to prohibit the generation of said audio information if said window (81, 102) is selected for a longer time than a predetermined period of time. 8. Decoder as stated in claim 3 and one of claims 4 - 6, and where the emitting equipment (20) is arranged to automatically issue said request when said window (81, 102) has been selected for a predetermined period of time. 9. Decoder as stated in one of claims 4 - 7, and which includes equipment (20) for automatically repositioning the cursor (83, 110) if a window (81, 102) is selected which displays a program or a channel that full audio and video access to. 10. Decoder as stated in claim 9, and where the repositioning equipment (20) is adapted to relocate the marker (83, 110) after the expiration of a predetermined period of time. 11. Decoder as set forth in one of claims 4 - 10, and comprising equipment (20) for changing an attribute of the cursor (83, 110) depending on a characteristic of either the program or the channel displayed in a selected window (81, 102). 12. Decoder as stated in claim 11, and where said changing equipment (20) is arranged to change the color of the marker (83, 110) depending on said characteristic of either the program or the channel displayed in the selected window (81 , 102). 13. Decoder as specified in claim 11 or 12, and which includes equipment (26) for receiving data for assigning said characteristic from a hand-held remote control (25) connected to the decoder and equipment (20) for assigning said characteristic in response to said received data. 14. Decoder as stated in one of claims 4 - 13, and which comprises equipment (31) for tuning the decoder to the channel displayed in the selected window (81, 102). 15. Decoder as set forth in one of claims 4 - 14, and comprising equipment (20) for generating a display (84) comprising information relating to the program displayed in the selected window (81, 102). 16. Decoder as stated in claim 15, and comprising equipment (23) for communicating with a communication center to obtain said information relating to the program displayed in the selected window (81, 102). 17. Decoder as stated in claim 16, and where said communication equipment comprises a modem (23) to call up said communication center for delivery of a request for said information to the communication center. 18. Decoder as set forth in one of claims 4 - 17, and comprising equipment (20) for generating a display comprising a schedule of upcoming programs for the channel displayed in the selected window (81, 102). 19. Decoder as stated in claim 18, and where the schedule of upcoming programs includes a text presentation of the program schedule information. 20. Decoder as stated in claim 18 or 19, and where said plan of upcoming programs comprises a display of several pictorial representations (122) linked to respective upcoming programs in respective windows in the mosaic formation (120). 21. Decoder as stated in claim 20, and where at least one of the amount of pictorial representations (122) includes the video (tape) length associated with the respective upcoming program. 22. Decoder as stated in claim 1, and where said receiving equipment (26) is adapted to receive said access rights from a hand-held remote control (25) connected to the decoder (13). 23. Decoder as stated in claim 22, and where said receiving equipment (26) is adapted to receive a PIN code from the hand-held remote control (25), the decoder comprising equipment for authenticating the received PIN code and by authenticating the received PIN code, to allow the receipt of access rights. 24. Decoder as stated in one of the preceding claims, and comprising equipment (20) for prohibiting the generation of at least part of the video information in said window (81, 102) depending on the access rights of a program or channel which is displayed in the relevant window (81, 102). 25. Decoder as stated in claim 24, and which comprises equipment (20) for controlling the presentation of an image (still image) in said window (81, 102) instead of said at least one part of video information. 26. Decoder as specified in claim 25, and where said image comprises a logo associated with the channel displayed in said window (81, 102). 27. Decoder as specified in claim 25, and where said image comprises an image linked to the program displayed in said window (81, 102). 28. Decoder as stated in claim 24, and which comprises equipment (20) for controlling the display of further video information in said window (81, 102) instead of said at least one part of video information. 29. Decoder as set forth in one of the preceding claims, and comprising equipment (20) for generating a message (86) informing a user of the access rights to a program or a channel upon positioning the cursor on said window (81, 102) which shows the aforementioned program or channel. 30. Decoder as stated in one of the preceding claims, and which comprises positioning control equipment (20) to control the relative positions of said windows (81, 102) within the mosaic formation (80, 100). 31. Decoder as stated in claim 30, and where said positioning control equipment (20) is arranged to control the relative positions of said windows (81, 102) in response to received access rights to channels or programs displayed in said windows (81 , 102). 32. Decoder as stated in claim 30, and where said positioning control equipment is arranged to control the relative positions of said windows (81, 102) in response to received window positioning data to control the relative positions of said windows (81, 102) within the mosaic formation (80, 100). 33. Decoder as specified in claim 32, and which comprises equipment (26) for receiving said window positioning data from a hand-held remote control (25) connected to the decoder (13). 34. Decoder as set forth in one of claims 30 - 33, and where said positioning control equipment is arranged to control the relative positions of the windows (81, 102) in the mosaic formation (80, 100) in accordance with a program characteristic for programs that are normally displayed on the channels displayed in the windows (81, 102). 35. Decoder as stated in claim 34, and where said positioning control equipment is arranged to group together windows (81, 102) showing channels that have the same program characteristic. 36. Decoder as stated in claim 34 or 35, and where said positioning control equipment is arranged to group together windows (81, 102) which show channels which normally show programs which have the same theme. 37. Decoder as specified in one of claims 34 - 36, and where said positioning control equipment is arranged to group together windows (81, 102) which show channels which normally show events with payment per display. 38. Decoder as set forth in one of claims 30 - 37, and wherein said positioning control equipment is arranged to hold a window (81, 102) showing either a particular channel or a particular program, in a constant position in the mosaic formation ( 80, 100). 39. Decoder as stated in claim 38, and where said window (81, 102) is the window in the mosaic formation (80, 100) which displays the channel that was shown immediately before the display of the mosaic formation (80, 100). 40. Method for controlling the presentation of several digital television channels in respective windows (81, 102) in a mosaic formation (80, 100), characterized in that it includes receiving access rights for either a program or a channel and that a user in accordance with the received access rights are prohibited from full audio and visual access to said one program or channel when it is displayed in a window (81, 102). 41. A method as set forth in claim 40, wherein access rights are received together with audiovisual data to create the mosaic (80, 100). 42. Method as stated in claim 40 or 41, and where the marker (83, 110) is generated to be displayed together with the mosaic formation (80, 100), said marker and said windows (81, 102) in the mosaic formation (80, 100) ) are optionally movable relative to each other to enable selection of a desired window (81, 102) within the mosaic formation (80, 100). 43. Method as specified in claim 42, and where audio information relating to a specific channel is generated in response to the marker (83, 110) being placed on the window (81, 102) which displays said specific channel. 44. Method as stated in claim 43, and where the generation of said audio information is prohibited in accordance with received access rights. 45. Method as stated in claim 44, and where the generation of said audio information is prohibited if the window (81, 102) is selected for a longer time than a predetermined time period. 46. Method as stated in one of the claims 42 - 45, and where the cursor (83, 110) is automatically repositioned if a window (81, 102) is selected which displays a program or a channel to which full audio and video access is prohibited to. 47. Method as stated in claim 46, and where the marker (83, 110) is relocated after the expiry of a predetermined period of time. 48. Method as stated in one of the claims 42 - 47, and where an attribute of the marker (83, 110) is changed depending on a characteristic of at least the program or the channel displayed in the selected window (81, 102) . 49. Method as stated in claim 48, and where said marker's color changes depending on said characteristic of at least the program or channel that is displayed in the selected window (81, 102). 50. Method as stated in claim 48 or 49, and where data for assigning said characteristic is received from a hand-held remote control (25), said characteristic being assigned as a reaction to said received data. 51. Method as stated in one of the claims 42 - 50, and which comprises that the decoder (13) is tuned to a channel that is displayed in the selected window (81, 102). 52. Method as stated in one of the claims 42 - 50, and which includes a step where a display (84) is generated which includes information relating to the program displayed in the selected window (81, 102). 53. Method as stated in claim 52, and which comprises communicating with a communication center to obtain said information relating to the program displayed in the selected window (81, 102). 54. Procedure as specified in claim 53, which includes calling the said communication center to deliver a request for said information to the communication center. 55. Method as stated in one of the claims 42 - 50, and which includes a step where a display is generated which includes a plan of upcoming programs for the channel that is displayed in the selected window (81, 102). 56. Procedure as specified in claim 55, and where said plan of upcoming programs includes a text presentation of the program plan information. 57. Method as stated in claim 55 or 56, and where said plan of upcoming programs comprises the display of several pictorial representations (122) linked to respective upcoming programs in respective windows in a mosaic formation (120). 58. Method as set forth in claim 57, and where at least one of the said quantity of pictorial images includes the video (tape) length associated with the respective upcoming program. 59. Method as stated in claim 40, and where said access rights are received from a hand-held remote control (25). 60. Method as stated in claim 59, and where a PIN code is received from the hand-held remote control (25) and the received PIN code is authenticated in order, upon authentication of the received PIN code, to allow the receipt of access rights. 61. Method as stated in one of the claims 40 - 60, and where the generation of at least part of the video information in a mentioned window is prohibited depending on the access rights of a program or a channel displayed in the relevant window (81, 102). 62. Method as stated in claim 61, and where an image (still image) is displayed in said window (81, 102) instead of said at least one part of video information. 63. Method as stated in claim 62, and where said image includes a logo associated with the channel displayed in said window (81, 102). 64. Method as stated in claim 63, and where said image comprises an image linked to the program displayed in said window (81, 102). 65. Method as stated in claim 61, and where further video information is displayed in said window (81, 102) instead of said at least one part of video information. 66. Method as stated in one of the claims 40 - 65, and where a message is generated that informs a user of the access rights to a program or a channel when a window (81, 102) is selected which displays said program or channel. 67. Method as stated in one of the claims 40 - 66, and which includes that the relative positions of said windows (81, 102) are controlled within the mosaic formation (80, 100). 68. Method as stated in claim 67, and where the relative positions of said windows (81, 102) are controlled in response to received access rights to the channels or programs displayed in said windows. 69. Method as stated in claim 67, and where the relative positions of said windows (81, 102) are controlled in response to received window positioning data for controlling the relative positions of said windows (81, 102) within the mosaic formation (80, 100). 70. Method as stated in claim 69, and where said window positioning data is received from a hand-held remote control (25). 71. Method as stated in one of the claims 67 - 70, and where the relative positions of the windows (81, 102) in the mosaic formation (80, 100) are controlled in accordance with a program characteristic of the programs that are normally shown on the channels shown in the windows. 72. Method as stated in claim 71, and where the windows (81, 102) which display channels which have the same program characteristic are grouped together. 73. Method as stated in claim 72, and where the windows (81, 102) which display channels which normally display programs which have the same theme are grouped together. 74. Procedure as stated in claim 72, and where the windows (81, 102) which show channels which normally show events with payment per display are grouped together. 75. Method as stated in one of the claims 69 - 74, and where a window (81, 102) showing a particular channel or a particular program is maintained in a constant position in the mosaic formation (80, 100). 76. Method as stated in claim 75, and where said window (81, 102) is the window in the mosaic formation (80, 100) which displays the channel that was displayed immediately before the display of the mosaic formation (80, 100).